The main source of EPA formulations to date is either fish oil or krill. In the case of fish oil, there are several problems: depletion of fisheries, a relatively low EPA content, DHA and the other six Omega-3 compounds in the mixture, and a variance in EPA content based on natural variance within and between species. The presence of the five other Omega-3 compounds is problematic as they compete with EPA for access to protein receptors. Due to fisheries depletion, at least one producer of fish oil has had its Atlantic menhaden allocation reduced by 20% (on the internet at nutraingredients-usa.com/Industry/Omega-Protein-s-Atlantic-menhaden-catch-to-be-cut-by-20).
The lower concentration of EPA in the raw fish oil and the presence of other near molecular weight components results in refining loss. Fish oil does not include any glycolipids. Phospholipids (PL) present in the raw fish oil tend to be removed through degumming steps adapted from the oilseed industry that as specifically designed to remove these components. Moreover, the transesterification to ethyl esters, one step along the most common refinement methods, also tends to destroy the phospholipids. Phospholipids in the final product would be less than 0.5 wt %.
With respect to krill oil, some of the same problems apply. Krill (Euphausia superba) naturally occur in the Antarctic. Krill is considered by many scientists to be the largest biomass in the world. Antarctic krill is fundamental to the survival of almost every species of animal that lives in the Antarctic or sub-Antarctic waters and island groups. Krill also contain eight Omega-3 fatty acids. Many of the fatty acids in Krill are nearly the same molecular weight as EPA and, therefore difficult to remove via refining. The other Omega-3s compete for receptors and, thus, decrease the EPA that is present. Krill, too, have a broad variation in the Omega-3 content and are very susceptible to breakdown of the PLs into FFA by both thermal and enzymatic action.
If everyone in the US and Europe ingested 2 g per day of EPA, a level that has been demonstrated to be effective in cardiovascular and mental health, there is not enough fish in the sea to provide a sustainable supply.